Laser radars, remote sensing, laser communications in free-space atmospheric line-of-sight and non-line-of-sight, as well as in satellite-to-ground and underwater environments are all affected to different degrees by optical turbulence. In this invention we disclose the atmospheric turbulence mitigation approach in view of communication systems; however this approach is applicable for a variety of other arrangements and turbulent media.
The atmospheric turbulence effect on an optical beam, noticeable as beam drift, spread, and scintillation, is the main source of impairments in the free-space optical communications. It leads to the decreased link capacity, bit-error-rate deterioration and sometimes unavailability of the transmission or fading. Adaptive optics schemes are widely used to correct wavefront phase corrupted by turbulence. Adaptive optical systems require direct measurement of the wavefront phase using wavefront sensors such as a Shack-Hartmann sensor or a shearing interferometer, followed by some type of wavefront reconstruction and conjugation. In the presence of the strong phase and intensity fluctuations characteristic of near-earth propagation paths, these types of systems tend to perform poorly. Furthermore, such systems cannot compensate for fast phase change; their operation speed is limited by the hardware response as well as data processing time.
There is a need for an efficient solution on turbulence effects mitigation in optical systems with laser beam propagation through the atmosphere.